The Electric Boat Thread

Jeremy Harris

100 MW
Joined
Oct 23, 2007
Messages
4,208
Location
Salisbury, UK
There's been some interest in an electric boat project I mentioned in the "mounting hall sensors to RC motors" thread in the "E-Bike non-hub motors" area, so I thought I'd transfer the topic here, where it might be more appropriate.

I've converted a cheap RC motor (a Towerpro 5330-10t) to run far more slowly and also fitted hall sensors to it, with the intention of building a very light power system for an electric canoe. Details of my motor mods can be found starting here:http://endless-sphere.com/forums/viewtopic.php?f=28&t=9061&start=105#p149542.

I was originally going to use a reduction drive to gear the prop down, but the losses are quite high - it takes about 24W just to turn the belt reduction.

The canoe I'm planning to build is the Selway Fisher Raven on this site: http://www.selway-fisher.com/Opcan16.htm. It's a ply, stitch-and-glue, open canoe. It seems to need around 40 watts or so to travel at 3.5 to 4 kts. It's maximum hull speed is about 5 kts, but it would need around 200 watts to reach it. My plan is to build a cruising boat that I can use to travel inland waterways and lakes at normal paddling speed, hopefully with some solar cells to augment range and allow charging when not moving.

The finished canoe should look like a scaled-down version of a typical Victorian electric river canoe like this one:

Brambd1.gif


Cedric Lynch (of Lynch Motor/Agni Motor fame) has already built a solar powered canoe:

DSCF0540.JPG


Although I've already bought the plans for the Raven canoe, I'm still not wholly convinced that it's the right boat. Part of me wants to build a slipper launch, like a scaled down version of this one:

PICT0593w.jpg


First job is to get the propulsion system finished and test the thrust vs power I can get. That will then help me to decide which boat design to go for in order to try and get a totally solar powered boat.

Jeremy
 
I live next to a river and I've been thinking about putting electric trolling motors on a boat and using my bike battery pack for power. Motor and prop in one package. 3 motors in series for 36v pack ........ :idea: It's on the back burner, to many projects already
 
Interesting boat, Warren. It'd cost too much to ship over here, though, otherwise I might have been interested. Out of interest, did you find that roll stability was adversely affected without paddling? This is something I've been wondering about, as it seems that paddling/rowing adds a significant stabilising effect. I may need a boat with a bit more beam than a narrow canoe just to stop it being a bit too tender.

Jeremy
 
Jeremy,

Great timing for an e-boat thread. I'm just finishing a move into a new house giving me space and time to complete my electric 4.8m catamaran. It will serve as the testbed and learning experience to build a large 10m version for deep sea fishing. For construction I'm going with sailboat designer Bernd Kohler's lightweight plywood/epoxy/fiberglass construction method http://www.ikarus342000.com/CATpage.htm . The 4.8m cat is designed to weigh only about 75kg with rigged for sailing, and I'm shooting for the same as an e-cat without the batteries.

For the big one I need about 1500W for 6-7 knot trolling, so I can run on batteries while fishing. For the higher speed runs out and back I'd run off of the generators located in each hull combined with sail wing assist.

John
 
Hi Guys,

My pedal powered kayak is located in the Chicago suburbs.

Straight line stabilty is scary but managable without any amas (side floats). When you turn, the boat leans into the turn, which is fine. As you are going through the turn, you naturally become upright again, also fine. When you turn the rudder again to go straight, you are then leaned to the outside or the turn, which is really scary.

Because of this I added the floats shown in the picture. They just skip along the wave tops and don't add much drag, if any. The boat feels very safe with the side floats.

This is a 20 ft boat, and it is very fast. I have been racing it once per year, but now I want to build a new one...

-Warren.
 
What I'd really love to have is a multi-seater E-flyak.. an electric hydrofoil kayak. That would be some awesome family fun right there man.

http://www.youtube.com/watch?v=bQRtgEIs--k
 
I used to work for Rio Lago Cruise, a boat rental/charter company located in the middle of Phoenix on one of our little man-made lakes. They have developed a few proprietary electric boats that they use commercially:

http://www.riolagocruise.com/elecdesc.html

In addition to the big charter boats, they offer rentals of electric converted runabouts and canopy cruisers (little 14' pontoon boats).

The parent company, ETEC, was responsible for developing the boats' power systems and also seems to be involved with some infrastructure projects:

http://www.etecevs.com/home.php
 
vanilla ice said:
What I'd really love to have is a multi-seater E-flyak.. an electric hydrofoil kayak. That would be some awesome family fun right there man.
http://www.youtube.com/watch?v=bQRtgEIs--k
Hehe...settle down vanilla... Any kinda weeds are killer for foils. And any flotsam... well, braking (breaking) speeds can be dramatic. Fun, yah, but "family style", not so sure. I've sailed at over 30kts on foils and yah it was pretty dramatic, but also quite a hammering as the boat and crew are slapped (pounded) as the craft shot through the waves. Totally high performance speed-wise, but I'm not convinced foils make for a well-rounded (safe/low-maintenance) boat!

That vid of the Flyak is impressive as heck :twisted:
tks
Lock
 
Ok, a solo hull then. The E motor would compliment the hydrofoil well since it takes relatively high amount of power (especially for us non-athletes) to get it up on the foil. Kind of envisioning the flyak to jetski relation like the ebike to scooter. Less speed, more efficiency, more practical/cheaper to E, but still fun.
 
Being from this side of the pond, and seeing many of the linked designs are based on Canadian canoes, I'll suggest looking at some other types developed in North America but from Old World roots. They are handy, pleasing and easy building boats. I'm thinking of the dory, scow and batteau types particularly. Flat bottoms, plenty of flare, nicely rockered and don't have to be heavy. You can sail 'em, row 'em, scull or pole them. Drag 'em up onto the mud or snow. An overall stable, efficient and aesthetic platform for an electric experiment, IMO.

If you can get a copy of "American Small Sailing Craft - Their Design, Development, and Construction" by Howard L. Chapelle - ©1951 from your library, you'll find lots of small boat designs with historical comment on their usage, development and disappearance.

That slipper launch is too pretty to not want to build.
 
That Flyak is pretty amazing, especially as it's flying on so little power. A really fit paddler can apparently generate a bit of 100 watts (less than a cyclist, due to the smaller muscle groups being used), so a suitable light weight electric power system would certainly make for a really fun boat. Not what I have in mind, but really neat all the same.

There's a fairly strong history here of building big, fat, Canadian styler canoes fitted with electric motors. They were very popular over 100 years ago, during the late Victorian, early Edwardian period, as sedate river cruising craft, used mainly on the river Thames. I think they chose the canoe design for low resistance when compared to more conventional river craft of the time. Unlike the original Canadian birch bark canoes, these Victorian ones were usually built using clinker construction, often with larch planks. The more modern version use ply lapstrake construction, although I'm looking at building using stitch-and-glue ply.

I've been doing a fair bit of reading up on low resistance hull design, including looking long and hard at some of the simple designs from Phil Bolger. I keep getting drawn back to the slipper launch though, as it's surprisingly simple in construction. I've drawn up a tandem two seat slipper hull, for ply stitch-and-glue construction, using this excellent shareware layout designer: http://www.carlsondesign.com/#Utilities (scroll down to "hull designer"). Here's a simple graphic model - I think I have the proportions about right now. I've narrowed the beam to better suit the reduced overall length (15'8") and keep the boat in proportion. The hull is flat bottomed at the stern and the transom sits just clear of the water for low drag. The hull panels will just fit on four sheets of ply.

3462994717_420ecbc8e9.jpg


Jeremy
 
Looks good! You've certainly done your homework. Shouldn't take too much to get it up on its step.
The deck area is a natural for photovoltaic cells.
Your work generally amazes me so please have lots of fun and keep us posted.
 
Nice photo of the Sneakeasy. I'll admit to this design being the one that made me look closer at the simple designs from Phil Bolger - he seems very adept at producing easy to build boat designs that are also well-known to have a relatively low hull resistance.

I think I may opt for converting a canoe initially, just to do some power unit development. I've been giving the stability issue some thought, including some ideas of ways to counteract that "adverse roll" effect that Warren has helpfully pointed out.

I've now started to build an experimental stern tube assembly, using a length of 1" x 16g alloy tube with a machined flange brazed to the end to fit the direct-drive motor. I've ordered a length of 12mm diameter stainless steel tube to act as a prop shaft. This will be directly coupled to the motor shaft and run in a bearing at the prop end, with a simple lip seal to keep the water out. Hopefully this will be relatively low drag; I'm hoping that the slight reduction in motor efficiency from running at low-ish rpm will be offset by the large reduction in drag from not using a reduction drive. If this doesn't work, then I will need to looking at bigger diameter, lower Kv, motors, perhaps a modified bike hub motor or perhaps an "alter-motor" using a motorcycle alternator core.

Here's a photo of the motor mounted on the stern tube.

3464297743_2f9a3fa78c.jpg


This assembly weighs just under 1kg (around 2.2 lbs) so is pretty light and on track for my target of no more than 10kg for the complete power system, including battery pack.

As an aside, that machined flange was simply push fitted on to the end of the tube and then brazed with Technoweld (see here: http://www.techno-weld.co.uk), a low-temperature alloy "welding" process that is pretty easy to do at home with a standard blowtorch.

Jeremy
 
mrgarci1 said:
I used to work for Rio Lago Cruise
Man, there's a blast from the past... How're they doing anyway? IIRC the original ownership of Rio Lago capsized (financially) shortly after launch and ETEC took over because Rio Lago still owed ETEC for the electrics.

What was interesting for me at the time was the ETEC fast charge capability...
Lock
 
talking about eltric boat.

i got a small min kota 17 pound here.

would like to get some info on how long it could last on my kayak.6 but i would have to guive you all the battarie data for this.?


joco
 
I run 2 motorguide motors on a 16 foot aluminum boat fully rigged. Front and Rear. With both on at the same time, I can go 4 mph on 12volts. With (2) 115ah 12v batteries, I can easily go for 12 hours on the lake at medium/high speeds.
 
That's useful info, particularly as I've read reviews about the Motorguide units being a bit more efficient than the Minkota ones.

Assuming that you're discharging the batteries by no more than 80%, then it looks like your average power consumption is around 180 watts for the two motors, maybe a bit less. I suspect an alloy fishing boat is going to present at least double the water resistance of a canoe, may be more, so my guess as to the power needed might be close.

I'm hoping to be able to keep the average power drawn from the battery pack down to around 70 watts, hopefully less, although this will depend very much on optimising the design.

joco,
My guess is that a good estimate for the Minkota might be to have enough battery capacity to supply around 100 watts average power for the endurance you want, factoring in that a lead acid battery will only deliver 80% or so of its rated capacity. If you're using a 12V battery, then I'd guess that you may need around 10 Ah of capacity for every hour of endurance you want. If you're using a 24V battery pack, then you might need half this capacity per hour. You may find that these figures are a bit out, depending on the actual resistance of your kayak hull, but I suspect they are close enough for an initial set-up.

Jeremy
 
One of the delights of a canoe is being able to go up really shallow rivers. If you fix a motor through the bottom of the boat you immediately increase the draft of the boat. Also you introduce the potential leakiness of the hull/motor shaft joint. Also, you are opening yourself to difficulties deweeding the prop.
If you fix a 2" diameter bamboo pole, 6 foot long to the front of your cockpit and hang a float and motor on each end, you have done away with the problems mentioned above. What do you think?
 
paultrafalgar said:
...through the bottom ...increase the draft of the boat ...potential leakiness ...difficulties deweeding the prop.
Agree 1000%
Have also seen plans to affix Minnkota-type motors to the bottom of the rudder. Alternatively, might be able to run a chain drive through a pipe and mfgr.yer own electric outboard w/motor out of the water so only splashproof not fully waterproof? Even just go long-tail? Yah, anything to avoid throughhulls!
tks
Lock
 
I agree that it's be nice to keep the shoal draft capability, but even with an outboard you still can't motor up shallow water. Whatever way you look at it, prop drive needs enough depth of water to work, whether it be an inboard or outboard installation. In fact. you can "steal" a bit, to reduce the draft, with an inboard by building a shallow tunnel in the centre of the hull, which makes such a rig able to motor in shallower water than an outboard.

I'm really looking to build something for use in fairly slow moving, fairly deep, inland waterways and lakes. I want the best efficiency I can get from the whole system, and am not prepared to accept the 30%+ losses from any form of belt/gear/chain transmission (at these low power levels friction in the transmission really saps efficiency). Although a bike chain can be efficient at moderate power levels, I've found that it still saps around 10 - 15 watts or more. Better that the belt drive which needed about 15 watts to turn, but still a big loss.

I'm working on making the prop swing up for beaching and weed clearance and will post a picture IF I can get it to work. One option I've looked at is to run a "centreboard" case down the stern of the canoe, with the slot coming right out aft. This would allow the prop to just swing up behind the stern. The difficulty this arrangement has is with placing the rudder, but I'm trying to make it an "all-in-one" solution, with the rudder swinging up with the stern tube.

The advantage of the stern tube is that sealing is easy, just a lip seal on the lower end and fill the thing with light oil. The pressure of the oil matches the water pressure, so in practice the seal isn't really being asked to do much. The inboard end of the stern tube is above the water level, so needs nothing more than an ordinary sealed bearing.

Jeremy
 
`Kay... Don't know what I am talking about so I can think "freely" :lol:

Thinking paddlewheel...

...hang on... think of a four-foot wide cylinder that is the foot of a isosceles triangle where the apex joins to the stern with a joint like a bicycle head tube (so only motion is side-to-side), and the cylinder floats to provide lateral stability (instead of ama/proa) for the whole boat but also has built in magnets and coils so can be spun with electrons? So no chain or sprockets etc, direct drive brushless hub motor, wound for very low rpms? If cylinder is buoyant enough could add netting in the triangle for additional cargo space.

No weed problems (maybe) with paddlewheels? Triangle steerable via cables to provide steering?

Just my $0.02 Cdn :)
Lock
 
You'll need a patent for that idea, Lock, it's a goodun! :D
So to elaborate the arrangement is like an old-fashioned lawn-roller. Each end of the shafts there is a disc with many coil/magnets stuck around the periphery and the central roller has corresponding coils/magnet opposite those on the end caps. Along the length of the "drum" are lengthwise struts glue to the drum which act as paddle-wheels. And just like a push trailer for an ebike, the whole arrangement can be decoupled and left behind if you want a workout.
Nice!
You could probably use a stepper-type motor for such a slow rotating drum.
 
Back
Top